Various solid carbonaceous materials, e.g., coals such as anthracite, bituminous, subbituminous, lignites and brown coals, are employed as fuels in a number of applications. One of the largest consumers of such materials is the utility industry for use in the generation of electric power. Due to a general decrease in the economic growth in this industry, however, an evergrowing demand is being made of the producers and suppliers of coal to provide coals of greater heating value per unit weight to assist the utility industry in reducing the costs of electrical power generation.
Generally, as-mined coals, and particularly those coals ranked below bituminous, have nominal heating values of approximately 8,000 Btu per pound. It is known that, by drying the coal to remove a substantial proportion of the so-called inherent moisture or water retained within the ultra-fine structure of the coal, the heating value per unit weight of the coal can be increased significantly. However, drying of coal, while effecting the desired increase in its heating value, also renders the dried coal more easily oxidized and, therefore, more susceptible to undergoing spontaneous combustion, making the transportation and storage of the dried coal difficult at best. Additionally, the dried coal is more friable than its precursor as mined coal, resulting in an increase in particle size degradation of the dried coal during the subsequent handling thereof.
It also is known to pyrolyze as-mined coal at low temperatures [e.g., 500.degree. C. to 750.degree. C.] to form chars for use as fuels in plants for generating electric power. Again, although, such chars exhibit increased heating valves, these chars suffer from substantially the same difficulties in transportation, storage and handling as the dried coals.
Thus, there, exists a present need for an efficient and economical process for preparing a carbonaceous fuel of enhanced heating value but having a diminished capacity to ignite spontaneously and to generate fines during the subsequent transportation, storage and handling thereof. The process of the present invention fulfills this need.